Water treating composition



Patented Nov. 13, 1951 WATER TREATING COMPOSITION John W. Leflrorge, Anniston, Ala., assignor to Monsanto Chemical Company, St. Louis, Mo., a

I corporation of Delaware 'No Drawing; Application December 15, 1947,

- A Serial-No. 791,933

1 l This invention relates to improved water treating compositions and to an economically and commercially feasible method of producing same.

An object of the invention is to provide a water treating composition of improved solution rate which contains a water soluble molecularly dehydrated alkali metal phosphate having a molecular ratio of alkali metal oxide to P205 of about 1.0 to about 1.3, a compound or compounds which liberate a relatively water insoluble gas when contacted with water, and a wetting rate retarder comprising an aliphatic alcohol containing in the aliphatic radical from 6 to 12 carbon atoms per polar group, or more particularly from 6 to 12 carbon atoms per hydroxyl group.

Another object of the invention is to provide a water treating composition of substantially increased solution rate which contains a water soluble molecularly dehydrated sodium phosphate having a Na20/P205 molecular ratio of from 1.0 to 1.3, an alkalinity adjusting agent which liberates a substantially water insoluble was upon reaction with the above phosphate and an alcohol of the above type, which composition, upon contact with water, spreads out and disintegrates into fine particles, thus increasing substantially the surface of the. particles exposed to the dis.- solving action of. the water.

An additional object is to provide a water treating composition which contains a molecularly dehydrated sodium phosphate having a 'NazO/Pzos molecular ratio of' about 1.0, :sodium carbonate and an alcohol of the, above'type', which composition floats upon thesurface of water treated therewith until 'dissolve'd, or at least partially sinks toward the bottom of the dissolving vat and then is refloated by the buoying action of the liberated gas until completely dissolved.

A further object is'to provide a non-matting 'or non-lumping water treating composition including the above combination of ingredients which possesses a substantially improved solution rate over that of similar compositions not containing the above wetting rate retarder."

I Claims. (01. 252-175) Other objects and advantages will be apparent to those skilledin the art as the description proceeds.

Water soluble sodium metaphosphate is awell known and widely used water treatingrcompound which is available commercially in the form of up or lumps when added to water and settles to the bottom of the dissolving vat in the form of a sticky gummy mass which dissolves at an extremely slow rate.

The matting tendency of powdered sodium hexametaphosphate may be counteracted partially by mixing therewith sodium carbonates and other gas-liberating alkalinity adjusting agents, but this method of approach does not provide a satisfactory solution to the problem. For example, if such mixtures are added to water, matting or lumping does not take place to the extent that it occurs with powdered sodium hex-, ametaphosphate per se, but the wetting rate of the phosphate powder and the gas liberation rate are so rapid that the buoying action of the gas is not or" sufficient duration to insure rapid solution of the mixture. The result is that appreciable amounts of sodium hexametaphosphate sink to the bottom of the dissolving vat and form a phosphate residue which dissolves very slowly.

above problem by agglomerating mixtures of powdered sodium hexametaphosphate and sodium carbonates. This method achieved some measure of success, but it is subject to the disadvantage of being expensive and of causing an excessive amount of reversion which seriously impairs the water softening properties of th product.

I.have made the surprising discovery that if finely divided sodium. hexametaphosphate, so-. dium. carbonate and an. aliphatic alcohol of the above type are homogeneously blended together in the proportions hereinafter indicated, a water treating product of substantially improved solution rate is provided which has none of the objectionable properties mentioned above. Thus, the resulting composition is in a very convenient form to handle, that is, to take out of the container, measure and put into solution; it is also quickly soluble and does not mat up when introduced into water; and it can be very easily and economically produced on a commercial scale.

The sodium carbonate in the above composition serves'as an alkalinity adjusting agent and also as a means of developing. carbon dioxide which'causes the product to float on the surface of water. Thus; sodium carbonate liberates carbon dioxide by reaction with sodium hexametaphosphate and the liberated gas forms bubbles which attach'themselves to the particles of the phosphate product. These bubbles buoy up the particles and cause them to float on the water surface until completely dissolved.

The aliphatic alcohols oi the present invention are somewhat water repellent and retard the wetting rate of the sodium hexametaphosphate particles and this has the desirable effect of causing the bubbles produced by the liberated carbon cfioxideetoaattachz. themselves to the above particles with the result that the latter are buoyed up and floated on the surface of the water. The Wetting rate retarding action of the alcohols brings about a slower but.more. uniform reaction between the phosphate particles and'the sodium carbonate and therefore:v the liberatedi gas is able to float the particles upon=the*surface= of the water for a period long enough to effect rapid and complete solution. The alcohols-also disperse any floating lumps ofthe mixture which. form on the surface and this not only aids. in the prevention of matting but also increases thesurface of the particles exposed to the dissolvingi action: of the water treated:.

The problems of matting and slow: solution rate are not limited to. sodium hexametaphosphate as they are encountered inall oi'the water soluble molecularly dehydrated; alkali. metal phosphates having an alkali metal. oxide/P205 molecular ratio of from about 1.0. to about 1.3 andit is to be understood that the presentinventiorr is.directeds to allof.- the foregoing phosphates andparticularly to thesodium andpotassium phosphates within the above range.

It should be pointed out, however, that notall of the above phosphates fioat when blended with gasliberating. compounds and the aliphatic. a1oohols of the present invention; The tendency: of the phosphates within. the. above range to. float decreases as the molecular ratio of: the alkali metal oxide to P205 increases and ata ratio of 1.3 the product does not float at all; Inthe case of; the higher ratio materials, the. increased= solution-rate is. attributable to the disintegrating and spreading action of the aliphatic alcohol; which prevents the powdered material. from-lumping. or matting, and increases the'surfaoeof thepartioles exposed to the dissolving action. of the; water treated.

For amorecomplete understanding of the present invention reference is madeto the following examples which illustratexthe marked increase in solution rate obtained by incorporating an. alcohol of the type hereinbefore indicated with:mixtures. of sodium carbonate and water; soluble molecularly dehydrated; sodium phosphates. having a. Na-2O/P2Os .moleculanratio withimthe range of from 1.0 to 1.3;

Example: I.

A finely divided. phosphate product- (Calgon). composed of approximately 80.8% by.- weight. of sodium hexametaphosphate, 11.8% by weight. of tetrasodium pyrophosphate and-7.4% by weight of sodium acid pyrophosphate. was thoroughly mixed with,6% by weight of. sodium carbonate to forma substantially homogeneous mixture.. of. these. ma-' terials. A 5-gram sample of the product was added to a beaker containing a liter of water and the timerequired to.completely dissolve-this material without agitation was determined. It was found that a substantial proportion of the sample rapidly dissolved during the gas liberating stage, but as soon as thiswas over, a portionthereof sank to the bottom of the. beaker and formed a phosphate residue which dissolved-so slowly-that atotal of 11 minutes. was... required forcomplete solution.

A similar mixture was prepared exceptthat 0.15% by weight of octanol'wasuniformly blended therewith.

A 5-gram sample of thisproduct wasintroduced into a. liter of water. and its, solution rate determined in thermanner described above... It was found that instead of setting free carbon dioxide all at once; and leaving a slbwly dissolvi'ng residue" on the bottom of the beaker, the' alcohol caused the phosphate material to spread out on the surface of the water and liberate the above gasmore. slowlyand uniformly with the result that the product floated and completely dissolved withirnazperiodiof .4 .Erminutes.

Example II A.finely divided. phosphate composition consisting; essentially of sodium septaphosphate (NasP'zozz) was intimately mixed with 6% by weightof sodium carbonate and a 5-gram sample of the resulting product. was added to a liter of water for the-purpose: of determining-its solution rate. Asirr Example 118. substantial amount of the. product rapidly dissolved. duringv the gas; lib;- eration. period, .but .a. slowly dissolving residue: was formed; onthe bottom: of. the; beaker: and it: re:- quired'. 15 1 minutesto. achieve completesolutioniof the entire: sample.

The above-experiment was repeated usingv the samecomposition. to. which 0.5% by weight: of octanol. had& been: added and. intimately mixed;

resultingproduct dissolved: completely with,- outagitationzirra period of 12.5 minutes;

The. above; examples; show: that; the; problem of matting: or: lumping is solved. by; the addition of octanol; and that: the-solution; rate of: mixtures of: sodium; carbonate witlrthe;abovephosphates is thereby'increasedlto aasurprising degree:

Theschemicalcomposition oizthewater. treating productlmay; be; varied. widely.- to meet specific re quirements, but; for. optimum results; from. the standpoint 'ofidetergent and water-softening prop-.- erties; it: is:prefenred.to maintain: the; components thereof within the-limitsspecified in the following formulation.

Per cent by'weight Phosphate composition 9.6Jto: 88 A. gas; liberating alkalinity adjusting:

compound Ltd 10 Aliphatic alcohol containing 6:-12,:car-

bon atoms: per; polar: group" 0.02. to 2 Per cent byweight Phosphate composition 80. to 96 Gas liberating compounds 20. to. 2

Aliphatic alcohols containing:6 12.car-

bon atoms per. polar group- 0.0210 2 Phosphate. Composition? as. used: above. covers Watersoluble moleoularly. dehydrated alkalimetal phosphates having. an. alkali. metal oxide/P205 molecular. ratioioi about 1.0 toabout. 1.3.. Stated difierently, this expression-covers. the: above .water soluble moleoularly dehydrated= alkali metal phosphates. or mixtures, thereof. in any. of the formsshown in.the. g-raph- (Fig. 8) on. page 460 of. the. article. by E. R. Partridge .etal. which? ism-e.- ported volume 63. ot the; J. Amer., Chem; SQ-

ciety, 1941. The expression Gas Liberating Compounds includes alkalinity adjusting agents such as sodium percarbonate, sodium carbonate, sodium bicarbonate and other compounds or combinations of compounds which hydrolyze or react together in the presence of water to yield a substantially water insoluble gas.

The aliphatic alcohols employed in producing non-matting rapidly dissolving water treating products are those containing from 6 to 12 carbon atoms in the hydrocarbon radical per polar group or more particularly those containing from 6 to 12 carbon atoms per hydroxyl group. Examples of compounds within the foregoing class which have been successfully used are hexanol, octanol, decyl alcohol and dodecyl alcohol.

The amount of alcohol employed in the water treating product may fluctuate considerably, but it is preferably maintained within the range of about 0.02% to about 2% by weight. The optimum amount varies with the compound selected, but in general the higher the molecular weight or the greater the number of carbon atoms per polar group, the smaller is the amount of alcohol required. In the use of octanol, the best results are obtained by using this material in an amount equivalent to about 0.15 by weight.

In compounding the above product, the components may be mixed together in any desired order so long as thorough and uniform mixing is obtained.

The particle size of the alkali metal phosphates is not critical, but it is desirable to use material not coarser than 50 mesh, and preferably not coarser than 100 mesh.

The above description has been limited to compositions consisting essentially of water soluble molecularly dehydrated alkali metal phosphates, gas liberating compounds which yield a substantially water insoluble gas upon contact with water and an aliphatic alcohol of the class hereinbefore defined. The invention, however, is not restricted thereto as various alkalinity adjusting compounds in addition to those specifically mentioned may be incorporated in the above compositions. For example, caustic soda, sodium sulfate, sodium bisulfate, sodium bisulfite, sodium meta silicate, trisodium orthophosphate, sodium pyrophosphates, sodium polyphosphates having a NazO/P2O5 molecular ratio above 1.3 and mixtures of these, and also the corresponding potassium salts may be employed if desired.

Where the gas liberating compound yields gas upon contact with water irrespective of the pH of the composition, the above alkaline salts may be used in any desired proportions, but this is not true where gas-liberating alkalinity adjusting agents are employed. Thus, if sodium carbonate, sodium bicarbonate, sodium percarbonate or equivalent salts are used, the quantity of the alkalinity adjusting compound must be so proportioned as to provide a composition having a pH in 1 solution not exceeding about 8.0, otherwise matting will occur. The reason for this is that a pH above about 8 either prevents the reaction between the phosphates and the alkalinity adjusting agent from occurring or it retards the reaction rate to a point where the gas is not liberated rapidly enough to float or disperse the product. The result is that the phosphate composition sinks to the bottom of the vat and forms a very slowly dissolving residue.

The present invention is limited solely by the claims attached hereto as part of the present specification.

I claim:

1. A substantially non-matting water treating composition consisting essentially of a substantially homogeneous mixture of the following materials in the indicated proportions: a water soluble molecularly dehydrated sodium phosphate having a sodium oxide/P205 molecular ratio of about 1.0 to about 1.3, 80%-96% by weight; a compound selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium percarbonate, 20%-2 by weight; a straight chain aliphatic monohydric alcohol, containing from 6 to 12 carbon atoms, 0.02%-2% by Weight.

2. A substantially non-matting water treating composition consisting essentially of a substantially homogeneous mixture of the following materials in the indicated proportions: a water-soluble molecularly dehydrated sodium phosphate having a sodium oxide/P205 molecular ratio of about 1.0 to about 1.3, 88%-96% by weight; a compound selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium percarbonate, 4%-10% by weight; a straight chain aliphatic monohydric alcohol containing from 6 to 12 carbon atoms, 0.02%-2% by weight.

3. A substantially non-matting water treating composition in accordance with claim 2 wherein the water soluble molecularly dehydrated sodium phosphate is sodium hexametaphosphate.

4. A substantially non-matting water treating composition in accordance with claim 2 wherein the water soluble molecularly dehydrated sodium phosphate is sodium septaphosphate.

5. A substantially non-matting water treating composition in accordance with claim 2 wherein the aliphatic monohydric alcohol is hexanol.

6. A substantially non-matting water treating composition in accordance with claim 2 wherein the aliphatic monohydric alcohol is octanol.

7. A substantially non-matting water treating composition in accordance with claim 2 wherein the aliphatic monohydric alcohol is decanol.

8. A substantially non-matting water treating composition in accordance with claim 2 wherein the aliphatic monohydric alcohol is dodecanol.

9. A substantially non-matting water treating composition consisting essentially of a substantially homogeneous mixture of sodium hexametaphosphate, about 6% by weight of sodium carbonate and about 0.15% by weight of octanol.

10. A substantially non-matting water treating composition consisting essentially of a substantially homogeneous mixture of sodium septaphosphate, about 6% by weight of sodium carbonate and about 0.5% by weight of octanol.

JOHN W. LEFFORGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A SUBSSTANTIALLY NON-MATTING WATER TREATING COMPOSITION CONSISTING ESSENTIALLY OF A SUBSTANTIALLY HOMOGENEOUS MIXTURE OF THE FOLLOWING MATERIALS IN THE INDICATED PROPORTIONS: A WATER SOLUBLE MOLECULARLY DEHYDRATED SODIUM PHOSPHATE HAVING A SODIUM OXIDE/P2O5 MOLECULAR RATIO OF ABOUT 1.0 TO ABOUT 1.3, 80%-96% BY WEIGHT; A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM CARBONATE, SODIUM BICARBONATE AND SODIUM PERCARBONATE, 20%-2% WEIGHT; A STRAIGHT CHAIN ALIPHATIC MONOHYDRIC ALCOHOL, CONTAINING FROM 6 TO 12 CARBON ATOMS, 0.02%-2% BY WEIGHT. 